C1Upload displays a button whose label is set to "Upload" by default. You already mentioned above the code that can be used to change the text of the Upload button, which is the only property set for it. Could you please elaborate your query further, describing which image would you like to change for C1Upload. It would be helpful if you could share a screenshot describing what kind of C1Upload appearance are you exactly expecting so that we can accordingly guide you ahead with this issue.